The present disclosure generally relates to railroad maintenance machinery, and more particularly relates to machinery used for lifting up a rail tie close to a rail while performing spiking operations.
Conventional railroad maintenance machine operations include spike pulling, spike driving, tie boring, tie replacement, lag screw application, anchor removing, and other related tasks. Each machine is designed for mechanically performing a specific task under operator control. A nipper is typically located between workheads of the maintenance machine for pulling the tie up to the rail to secure a tie plate to the tie during the driving of spikes into ties, also known as spiking. A main nipper actuator controls up and down positions of the nipper, and an auxiliary actuator controls open and close positions of nipper hooks. The nipper hooks are constructed and arranged for grasping a lower surface of the tie and pulling it upwards toward the rail. A nipper frame is supported by guide blocks on the main machine frame, which are used to guide the nipper frame during reciprocal upward and downward movements.
As is well known in the art, the nipper travels downwardly toward the tie and, under operator control, penetrates the ballast surface to reach a predetermined depth below the tie. Specifically, depending on a zero velocity time period, the nipper automatically digs downwardly into the ballast until the nipper hooks reach a predetermined depth, the hooks close to grasp the tie for the spiking operation. Next, the nipper lifts up the grasped tie so that the tie, the tie plate, and the rail are held tightly together.
Generally, the set time period is sufficient to infiltrate the ballast and reach a safe distance for closing the hooks without damaging the tie. However, when the ballast is resistant to penetration due to, e.g., dense packing of ballast or otherwise inconsistent sections of the railroad track, the operator must manually override the downward operation of the nipper by opening the hooks and retracting the nipper upwardly and downwardly to prevent damage to the tie. Such damage occurs when the nipper does not fully penetrate the ballast and closes the hooks prematurely, thereby destructively pressing against side walls of the tie. This causes not only additional timely repair work, but also unnecessary costly expenses. Thus, there is a need for developing an improved system and method of an automatic nipping operation.